Project Summary Toxoplasmosis is caused by a single-celled apicomplexan, Toxoplasma gondii (T.gondii), which invades host cells through ingestion of uncooked infected meat or contaminated water. T.gondii infects 30% of the world?s population and the current cost of the disease in US itself is estimated to be $3B and rising. Current treatment regimen is effective only against acute infection and has severe side effects. Hence there is an urgent need for new drugs and drug targets. The genome of T.gondii, is predicted to encode 108 active kinases. Kinases have been shown to be involved in every aspect of the life cycle of T.gondii, from invasion of host cells to virulence. However, the lack of commercially available robust kinase assays has hindered T.gondii kinome-directed drug discovery. In this application, we aim to develop and validate assays targeted against the kinases essential to the T.gondii parasite?s life-cycle, which is responsible for transmission and disease pathology. These T.gondii kinase specific assays, based on our three-hybrid split luciferase system, will be further used for high throughput screening of a kinase targeted inhibitor library. These efforts are both significant and innovative as the identification of target specific inhibitors will not only provide pharmacophores for further drug development but also identify chemical probes for studying kinase biology and signaling pathways to provide new interventions.